1. Field of the Invention
The present invention relates to a switch used for mode selection and shift operation at the time of stepping speed change, in particular, a switch used for a transmission system including an automatic transmission capable of switching an automatic speed change mode allowing continuously variable speed change to or from a stepping speed change mode allowing stepping speed change ratio control (hereinafter, referred to as xe2x80x9cstepping speed change controlxe2x80x9d) like manual type multistage transmission.
2. Related Art
Japanese Patent Laid-open No. Hei 9-203460 discloses a transmission system including an automatic transmission composed of a hydrostatic type automatic transmission (hereinafter, sometimes referred to as xe2x80x9cHFTxe2x80x9d) and a sub-transmission connected to the automatic transmission in series. The hydrostatic type automatic transmission is configured such that a fixed displacement swash plate type hydraulic pump is connected to a variable displacement swash plate type hydraulic motor via a hydraulic closed circuit. In this transmission system, the automatic transmission includes an automatic speed change mode allowing continuously variable speed change and a stepping speed change mode allowing multistage speed change, wherein stepping speed change is started under the stepping speed change mode which is switched from the automatic speed change mode by a mode switch. This stepping speed change control can be performed just as a manual type multistage transmission by selecting a target speed change ratio from a plurality of predetermined speed change ratios by means of a shift switch.
Japanese Patent Laid-open No. Hei 9-264416 discloses a transmission system in which a mode switch and a shift switch are separately provided on a steering handle.
In addition to the above, known transmission systems, used with handlebar type vehicles include a shift switch provided on the left side of a handlebar, and a mode switch provided on a handle cover separated from the shift switch.
The above-described prior art transmissions of the type in which the mode switch and the shift switch are separately provided have specific disadvantages. One such disadvantage is that since switches specialized for mode selection and shift operation must be provided, the number of parts becomes large, and since the mode switch and the shift switch are different from each other in terms of opportunity of operation and operational manner, special care is required to prevent these switches from being erroneously used.
The transmission used for a handlebar type vehicle has another problem. Since the mode switch is provided at a location separated from the handlebar, a driver must separate his or her hand from the handlebar for each mode switching operation, with a result that the mode switching operation becomes complicated.
An object of the present invention is to solve these problems of the prior art transmissions.
To achieve the above object, according to the present invention, there is provided a transmission system including: an automatic transmission having a plurality of speed change modes including at least a continuously variable speed change mode and a steeping speed change mode; a sub-transmission connected to the automatic transmission, the sub-transmission being capable of switching one of a plurality of running ranges containing a forward range, a neutral range, and a reverse range to another; a mode switch for selectively switching either of the plurality of speed change modes of the automatic transmission; and a shift switch for switching one of speed change stages to another under the stepping speed change mode, a function of the shift switch and a function of the mode switch are collectively integrated into a common switch, and the common switch is selectively used as the shift switch or the mode switch.
In the above transmission system, the common switch may be configured to be usually used as the shift switch and used as the mode switch only when brake operation is confirmed or only when the running range becomes the neutral range; and further the forward running side of the running ranges may be configured as to include only one range.
According to the present invention, since the functions of the shift switch and the mode switch are collectively integrated into the common switch and the common switch can be selectively used as the shift switch or the mode switch, it is not required to provide switches specialized for mode selection and shift operation, with a result that the number of parts can be reduced. Additionally, because the shift switch and the mode switch can be disposed at one location, the mounting and usage of these switches become convenient.
According to a specific configuration in which the common switch is usually used as the shift switch and the common switch is changed into the mode switch only when brake operation is confirmed, the shift switch can be used as the mode switch under the condition that manual control is not carried out, with a result that the shift switch can be prevented from being erroneously used as the mode switch even in a running range. According to another specific configuration in which the common switch is changed into the mode switch only when the running range becomes the neutral range, the shift switch can be also prevented from being erroneously used as the mode switch.
According to a further specific configuration in which the front running side of the running ranges is switched by the sub-transmission, which generally includes two or more running ranges such as a low (L) range and a drive (D) range, the transmission can be configured to include only one running range by setting the automatic transmission such that the front running side is expanded to include the low side. Accordingly, it is possible to eliminate the need of switching one of the running ranges on the forward side to another, that is, to eliminate the laborious operation required for the conventional general sub-transmission, in which the driver""s hand must be separated each time the L (low) range is switched to or from the D (drive) range. Furthermore, since the speed change mode and the speed change stage under the stepping speed change mode can be switched only by operating the common switch, the speed change operation for running on the forward side can be performed without separation of the driver""s hand from the handlebar.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.